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If k is an integer greater than 6, all of the following must be divisi

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If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 06 Apr 2016, 07:12
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If k is an integer greater than 6, all of the following must be divisible by 3 EXCEPT

A. k(k + 3)(k - 1)
B. 3k^3
C. (k+1)(k+5)(k+6)
D. (k+2)(k-2)(k+3)
E. k(k+1)(k+2)
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 06 Apr 2016, 07:44
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Vinayprajapati wrote:
IF K is an integer greater than 6, then all the following must be divisible by 3 EXCEPT
a) k(k+3)(k-1)
b)3k^3
c)(k+1)(k+5)(k+6)
d)(k+2)(k-2)(k+3)
e)k(k+1)(k+2)


Since we are working with VARIABLE, We can be sure if the product can be shown as 3 consecutive numbers, by adding /subtracting 3 from any of the terms..

lets see the choices



a) k(k+3)(k-1)
(k-1)*k*(k+1) are consecutives BUT instead of k+1, we have k+3 in k(k+3)(k-1) ..
and if k+1 is div by 3, k+3 will not and k and k-1 will also be not div by 3..
so this is NOT necessary to be div by 3

b)3k^3
3 is there in the term, so TRUE

c)(k+1)(k+5)(k+6)
if K+1 is div by 3, k+1+3=k+4 will also be div by 3
so we have consecutive terms by adding 3 to k+1
k+4, k+5 and k+6..
TRUE

d)(k+2)(k-2)(k+3)
add 3 to k-2. it becomes k-2+3=k+1..
again 3 consecutive terms k+1, k+2 and k+3
TRUE

e)k(k+1)(k+2)
3 consecutive terms already
TRUE
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 06 Apr 2016, 07:26
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 06 Apr 2016, 09:18
I looked at this question and thought why would somebody make this question and post it here. then I saw that it is from GMATPREP. So now i assume this is one of those simple questions that make you think about your performance while doing the CAT. Algorithm's tricks.
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 06 Apr 2016, 19:31
I figured it out by taking K=7 and k=8
and option A is not divisible by 3 in case of k=8
so A is a answer.

Thanks !
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 13 Mar 2017, 16:36
I still don't understand this one why it would be choice A.
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 14 Mar 2017, 12:23
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 14 Mar 2017, 15:44
Got it now. Thank you!
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 07 Apr 2017, 06:49
chetan2u wrote:
Vinayprajapati wrote:
IF K is an integer greater than 6, then all the following must be divisible by 3 EXCEPT
a) k(k+3)(k-1)
b)3k^3
c)(k+1)(k+5)(k+6)
d)(k+2)(k-2)(k+3)
e)k(k+1)(k+2)


Since we are working with VARIABLE, We can be sure if the product can be shown as 3 consecutive numbers, by adding /subtracting 3 from any of the terms..

lets see the choices



a) k(k+3)(k-1)
(k-1)*k*(k+1) are consecutives BUT instead of k+1, we have k+3 in k(k+3)(k-1) ..
and if k+1 is div by 3, k+3 will not and k and k-1 will also be not div by 3..
so this is NOT necessary to be div by 3

b)3k^3
3 is there in the term, so TRUE

c)(k+1)(k+5)(k+6)
if K+1 is div by 3, k+1+3=k+4 will also be div by 3
so we have consecutive terms by adding 3 to k+1
k+4, k+5 and k+6..
TRUE

d)(k+2)(k-2)(k+3)
add 3 to k-2. it becomes k-2+3=k+1..
again 3 consecutive terms k+1, k+2 and k+3
TRUE

e)k(k+1)(k+2)
3 consecutive terms already
TRUE



When should one use plug in method to solve a question? Is this method of plugging in better?
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 22 Jun 2018, 11:37
Vinayprajapati wrote:
IF K is an integer greater than 6, then all the following must be divisible by 3 EXCEPT
a) k(k+3)(k-1)
b)3k^3
c)(k+1)(k+5)(k+6)
d)(k+2)(k-2)(k+3)
e)k(k+1)(k+2)


k(k+3)(k-1) will not be divisible by 3 when k=3n-1, where n is any positive integer
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Re: If k is an integer greater than 6, all of the following must be divisi  [#permalink]

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New post 16 Oct 2019, 20:45
Just test k=11.

Each answer choice but A will lead to a set of numbers divisible by 3.
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Re: If k is an integer greater than 6, all of the following must be divisi   [#permalink] 16 Oct 2019, 20:45
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If k is an integer greater than 6, all of the following must be divisi

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